The present invention relates to parts sorting systems.
Attention is called to U.S. Pat. Nos. 4,095,475; 4,200,921; and 4,287,769 to the inventor B. Shawn Buckley herein.
In batch processing of the nature discussed herein, batches of parts from 50 to perhaps 1000 are processed at one time. Batch processing, which represents 75% of the dollar value of parts manufacturing, is economically appropriate for those parts which are made in volumes of less than a million parts per year. However, batch processing is a labor intensive approach that results in high cost per unit relative to automated parts manufacturing or hard automation.
In hard automation, the volume of parts processed is high enough that a machine can be built and dedicated to the manufacture of a particular part. Usually a million or more parts per year are needed to justify economically such a dedicated machine. It is called hard automation because "hard" tooling is needed to manufacture a particular part. If the design of a part should change, often another machine must be built to automate its manufacture, even for relatively minor changes in the part's design. Despite the drawback of requiring special-purpose machines for each part design, hard automation remains the most economical method of manufacturing when millions of a part are to be made.
"Soft" automation is an attempt to apply hard automation principles to batch processing: it replaces the "hard" tooling with electronic computers. The computers can be quickly reprogrammed to manufacture a part of a different design without performing the task manually or redesigning the machine that makes the part. In metal cutting, "soft" automation incorporates numerically controlled (NC) lathes and milling machines; in warehousing, it incorporates automatic retrieval systems; in paint spraying and spot welding it incorporates industrial robots; in factory automation, it incorporates programmable controllers.
However, in parts handling systems the versatility of "soft" automation has not been realized. True, industrial robots can be programmed to manipulate a part in enormously complicated ways once given a part to manipulate. But, unfortunately, it has no versatile way of obtaining the parts in the first place. Each robot comes equipped with custom-tooled parts feeders, whose cost is typically three to five times the cost of the robot itself. The parts feeders, the dominant cost in a robot parts handling system, must be custom designed and installed for each part a robot manipulates. Thus the robot becomes a mere accessory to what is essentially a hard automation system. While the robot is versatile enough to handle a variety of parts, the system to which it is coupled is not.
Vision systems represent an attempt by "soft" automation experts to couple the robot to the parts that it must handle. Unfortunately, vision systems are expensive compared to manual methods. Although they hold the promise of enabling a robot to feed its own parts, presently they are not a practical way to do so. A versatile low-cost method of feeding parts to robots is required before "soft" automation comes to parts handling in manufacturing.
Feeding parts to a robot, or for that matter a dedicated automation machine, requires that the parts be properly oriented. Parts usually come in baskets or bins, oriented randomly. The task of a parts feeder is to ensure that the parts are presented to a robot in the same way for each part. For example, the cap of a ball point pen must be presented to a robot in a particular orientation for the subsequent mating to the body to occur properly.
In addition to orienting parts for soft or hard automation, inspection of the parts is also important. In hard automation, defective subcomponents can double the cost of assembling a typical component. The difficulty is downtime: defective parts jam a machine and require operator time to fix the jam. Stopping production to unjam a machine reduces the production rate significantly--enough to justify the highest quality parts. But high quality parts themselves are expensive so a compromise is reached between the increased cost of high quality parts and the increased cost of unjamming machines.
If low-quality parts were sorted prior to assembly by a dedicated automation machine, significant saving would result. Downtime due to jams would be eliminated, production rates would increase and manufacturing costs would be reduced. Robots used in manufacturing of parts could also benefit from using pre-sorted parts: jams in robot-based systems can often result in damage to the robots.
Accordingly, it is an objective of this invention to provide a parts orienting device which automatically feeds similar objects to an inspection region, detects their orientation through various sensors, and manipulates the objects to ensure that objects leaving the orienting device have only the desired orientation.
Another objective of the invention is a parts-sorting device which automatically feeds similar objects to an inspection region, detects the shape of the objects through various sensors and manipulates the objects to ensure the objects leaving the sorting device have only the desired shape or other sensed characteristics.
These and still further objectives are addressed hereinafter.
The foregoing objectives are achieved, generally, in an apparatus for sorting parts for the purpose of interfacing with an industrial robot or the like or for presenting those parts to a production machine or the like. A feeder transports a part into a sensing region where it is subjected to wave energy of a single or narrow-frequency band. Reflected or other wave energy resulting from the impinging wave energy is sensed at a multiplicity of places to provide signals from which amplitude information and phase information of the received wave energy can be derived with respect to each place. An analyzer extracts from the amplitude information and the phase information intelligence with respect to a geometry parameter and/or electromagnetic parameter the part, which, in turn, is used to sort the part. It will be appreciated that the geometry or electromagnetic parameters includes position data as well as shape data with respect to the irradiated part.